1. Field of the Invention
The present invention relates to hydroxyl functional oil polyol acrylic graft copolymers, coating compositions formed from the hydroxyl functional oil polyol acrylic graft copolymers, methods of coating substrates with the coating compositions, and substrates coated with the coating compositions.
2. Description of Related Art
Current art is primarily based on epoxy resin technology cured with amino resins and phenolics. Coating compositions formed from bisphenol A based epoxy resins have been used to coat packaging and containers for foods and beverages. However, there is a desire among some consumers and brand owners for coating compositions free, or substantially free, of bisphenol A for packaging and containers for food and beverages
U.S. Pat. No. 5,728,796 discloses a process which reacts an epoxide-containing compound with an aliphatic hydroxyl containing compound in the presence of a sulfonic acid catalyst. This process is used to form epoxy resins having high molecular weights.
U.S. Pat. No. 4,012,559 discloses a radiation curable coating composition having an acrylic copolymer, a polyfunctional compound having a molecular weight not greater than 2,000, and an epoxidized vegetable oil. It is explained that the cured compositions can be coated onto metal to form precoated metal products
Guo, et al., Rigid Polyurethane Foams Based on Soybean Oil, Journal of Applied Polymer Science, Vol. 77, 467-473 (2000) teaches the reaction of an epoxidized soybean oil with methanol to form an epoxidized soybean oil polyol that is used to prepare polyurethane foams for use in thermal insulation and packaging.
U.S. Patent Application Publication No. 2008/0302694 discloses a radiation curable coating composition having an epoxidized vegetable oil oligomer prepared from the reaction of an epoxidized vegetable oil and a hydroxyl functional acrylate or hydroxyl functional methacrylate in the presence of a sulfonic acid catalyst. This composition can be used as a coating for packaging materials in food storage.
U.S. Pat. No. 4,212,781 discloses processes for modifying an epoxy resin through a reaction with a copolymerizable monomer in the presence of an initiator. A graft polymer is formed from the epoxy resin by the grafting an addition polymer onto the aliphatic backbone of the epoxy resin. It is disclosed that the process is useful for making polymer blends for coating compositions.
There is a desire to produce packaging coatings that do not contain bisphenol A or are substantially free of bisphenol A. The hydroxyl functional oil polyol acrylic graft copolymers of the invention can be used in the preparation of coating compositions suitable, inter alia, as packaging coatings for food and beverage packaging and containers. They can be formulated to provide higher solids for application and improved corrosion resistance compared to some commercial epoxy coating systems.